ios - 添加 UIBarButtomItem 但它没有显示在界面上

Question

我正在尝试以编程方式向 viewController 添加一个返回按钮，但是它没有通过模拟器显示在界面上。我的代码中遗漏了一些东西？？有构建错误只是一个空白屏幕！

#import "ViewController.h"

@interface ViewController ()
@end

@implementation ViewController
- (void) performAdd:(id)paramSender{
   NSLog(@"Button got called");
}

- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

    self.view.backgroundColor = [UIColor blackColor];
    self.title =@"go Back";

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]
     initWithBarButtonSystemItem:(UIBarButtonSystemItemAdd)
     target:self
     action:@selector(performAdd:)];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
@end